There has been known a robot control apparatus that controls a robot in which a plurality of links is connected by joints. The robot control apparatus controls a motor provided at a joint portion of the robot and transmits power of the motor to a link via a speed reducer.
There is torsion in the speed reducer. Therefore, a robot control apparatus is proposed that improves a positioning accuracy by compensating for the torsion of the speed reducer. For example, the specification of U.S. Patent Application Publication No. 2010/0191374 proposes a robot control apparatus that compensates for torsion of a speed reducer by correcting a position command based on a difference between the output of an encoder provided on the output shaft side of the speed reducer and a predetermined position command.
However, in the above-described conventional robot control apparatus, an element of control delay is present between the output of the encoder and the position command, so that the position command needs to be corrected by performing adjustment according to the control delay. The control delay time changes depending on the responsiveness of a robot. Therefore, the delay time needs to be set according to the responsiveness of a robot, so that if the accuracy of a setting value is low, positioning cannot be performed with a high accuracy.